It is known to manufacture jaw members for electrosurgical instruments by an overmoulding process, in which components are assembled into a mould and flowable material is introduced into the mould to surround the components and form the completed jaw member. U.S. Pat. Nos. 7,150,097 & 7,922,953 are examples of such manufacturing methods. However, unless the manufacturing tolerances for the jaws are strictly controlled, there is a chance that when the jaws are assembled together to form a pair of jaws, the tissue-contacting surface on one jaw may not be exactly in the required orientation with respect to the tissue-contacting surface on the other jaw.